We present a perturbation result for generators of -semigroups which can be considered as an operator theoretic version of the Weiss-Staffans perturbation theorem for abstract linear systems. The results are illustrated by applications to the Desch-Schappacher and the Miyadera-Voigt perturbation theorems and to unbounded perturbations of the boundary conditions of a generator.
Martin Adler. Miriam Bombieri. Klaus-Jochen Engel. "On Perturbations of Generators of -Semigroups." Abstr. Appl. Anal. 2014 1 - 13, 2014. https://doi.org/10.1155/2014/213020